Bangkok: An international Rohingya crisis appeal has raised $278 million to help deal with one of the world's worst humanitarian emergencies, but that is less than half the amount experts say is needed.

United Nations and international aid agencies have appealed for $562 million to assist 1.2 million people, including Rohingya people living in sprawling refugee camps and Bangladeshis affected by the crisis.

Aid workers are scaling up their distribution of shelter and non-food items as winter takes hold in the camps.

Health workers are also widening vaccination programs in response to the rapid spread of diseases, including highly contagious diphtheria.

More than 655,000 Rohingya Muslims have fled Myanmar's Rakhine state since August 25, the day the country's army launched systematic attacks on Rohingya villages in what the United Nations calls "text-book ethnic cleansing" and "very likely" crimes against humanity.

Survivors have told of atrocities including organised rape, torching of villages and the slaughter and burning of children.

In Australia, an appeal for funds in conjunction with the Australian Red Cross and the refugee agency UNHCR has raised millions which are being matched dollar for dollar by the Australian government in a campaign supported by Fairfax Media and the ABC.

The Australian Red Cross Myanmar Crisis appeal has raised almost $4 million, including the government's contribution.

Jess Letch, the Red Cross's disaster and crisis response manager, said money raised goes towards "providing healthcare for those who are sick and injured, running our field hospitals and mobile health clinics, ensuring families are able to access clean water and sanitation, providing essential relief items, as well as psychological support for those who need it."

Ian Woolverton from Save the Children said "so far we have raised over $500,000, which is a great effort."

"The needs are massive with children and families living in the most appalling conditions," he said.

Oxfam has raised about $300,000.

"Humanitarian support for the Rohingya refugees has not been able to keep pace with the scale of the crisis and needs to be urgently increased," said Oxfam Australia's Chief Executive Dr Helen Szoke.

"With the crisis likely to go on for years, it is now time for donors to support longer term needs."

The Australian government has pledged $30 million of its more than $3 billion-a-year overseas aid budget for the Rohingya crisis, which includes up to $5 million to match money raised.

The government is also supporting the delivering of programs by Care Australia, Caritas Australia, Oxfam, Plan International Australia, Save the Children Australia and World Vision Australia.

Foreign Minister Julie Bishop said "I urge the Australian public to give generously. Your support will help to deliver life-saving assistance to those caught-up in this crisis."